Season the steak well. Heat a lightly oiled griddle or frying pan. Sear the steaks for 2 mins each side, then remove and leave to rest for 5 mins. When rested, thinly slice.
Mix the dressing ingredients together with 1 tbsp water until the sugar is dissolved. Arrange the spinach, beef, papaya, herbs, cucumber, spring onions and chilli on a platter. Pour the dressing over half the salad and sprinkle with the crispy onions. Serve the remaining dressing on the side or save for making another salad.
